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Leaflet No. 245 . . . United States Department of Agriculture
Palpating Domestic Rabbits
to Determine Pregnancy
By Allen E. Suitor, Biological Aid. U. 8. Rabbit Experiment Station, Font ana,
Calif.. Bureau of Animal Industry, Agricultural Research Administration
RABBIT BREEDERS have long felt a need for an accurate method
for determining pregnancy in domestic rabbits. This would
make it possible to feed the pregnant and nonpregnant does properly
and to rebreed promptly those does that fail to conceive. Such a pro-
cedure would save feed and the labor of supplying unnecessary nest
boxes.
The common practice of "test mating" does (placing the doe in
the buck's hutch periodically to determine whether or not she has con-
ceived )_ is not satisfactory, owing to the fact that some does will accept
service when pregnant and others will refuse to mate when they are
not pregnant. Diagnosing pregnancy by noting the development of
the abdominal region and the doe'- gam in flesh as the period of gesta-
tion advances i- not dependable and the diagnosis cannot be made until
late in the period.
Palpation Method
Palpating (feeling the developing young in the horns of the uterus
with the thumb and ringers) is a quick and accurate method :'<>r de-
termining pregnancy. The method for restraining the doe for pal-
pating is illustrated on page 1. The ears and a fold of -kin oxer the
shoulder- are held in the right hand: the left hand is placed under the
body between the hind leg- and slightly in front of the pelvis; the
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2 LEAFLET 2 4 5, UNITED STATES DEPARTMENT OF AGRICULTURE
thumb is placed on the right side and the fingers on the left side of the
horns of the uterus for palpating the embryos.
It is very necessary that the doe be handled gently and that she
should not struggle while being palpated because, if the abdominal
muscles are tense, it will be difficult to distinguish the horns of the
uterus and the developing embryos from the other organs. The doe
may be palpated in her own hutch or, if more convenient, she may be
placed on a table covered with feed sacks to prevent slipping.
Time of Palpating Important
The rabbit breeder can develop the technique for accurately diag-
nosing pregnancy by palpating 14 to 16 days following mating. At
this period, the embryos in the horns of the uterus have developed into
marble-shaped forms that are easy to distinguish as they slip between
the thumb and fingers when the hand is gently moved forward and
backward and a slight pressure is exerted. Caution must be used in this
operation, because if too much pressure is exerted, the tissues may be
bruised or torn loose from the walls of the uterus and a toxic condition
or abortion may result.
There is less danger in palpating at 14 to 16 days than at a later
period. However, diagnosing pregnancy after the 16th day of the ges-
tation period is more complicated because the developing embryos
are so large that they may be confused with the digestive organs.
There is also less danger of bruising the tissues or causing the embryos
to be torn loose from the walls of the uterus at the 14- to 16-day period.
The inexperienced rabbit owner should make examinations at this
period and then as he develops the technique and attains confidence
in the operation, he may be able to develop the ability for diagnosing
pregnancy accurately as early as the Tth or 8th day. The chief ad-
vantage to be derived from palpating as early as the 7th or 8th day
would be in the case of the breeder selling bred does. When it is
Figure 1. — Specimens (the digestive tract removed) showing the relative loca-
tion and size of the horns of the uterus of a nonpregnant doe (left) and the em-
bryos in the horns of the uterus of a doe at the end of 10 days' pregnancy
(right).
PALPATING RABBITS TO DETERMINE PREGNANCY 3
desirable to ship bred does considerable distance, diagnosing preg-
nancy at this early date makes it possible to have these does arrive
at their destination in sufficient time to become settled and acquainted
with their new environment, with the minimum risk of complications
at kindling.
In palpating a doe to determine pregnancy, the operator must take
into account the relative size and location of the horns of the uterus
and the embryos as pregnancy advances. Figure 1 illustrates the com-
parative size of the horns of the uterus of the nonpregnant doe (left),
the horns of the uterus lying just in front of the pelvis, and those of a
doe at the end of 10 days' pregnancy. The horns of the uterus have
expanded to accommodate the developing embryos.
As the period of gestation advances, the embryos grow larger and
the horns of the uterus are pushed forward, as indicated in figure 2.
Figure 2. — Specimens with the digestive tract removed, showing the relative loca-
tion and side of the horns of the uterus and the developing embryos of a doc
at the end of 14 days' pregnancy (left) and of a doe at the end of 21 days'
pregnancy (right).
Figure 3 illustrates the continual increase in size of the horns of the
uterus and the embryos as pregnancy advances. The ruler at the bottom
of the illustration gives a means for arriving at a comparative estimate
of the size of the embryos. In each case, an embryo has been removed
from the respective horn of the uterus and placed just above the ruler.
The 10-day embryo was so small that is does not show in the cut. By
comparing the 1-t- and 21-day specimens it will be seen that the growth
of the embryo is very rapid.
Appearance of the Nonpregnant Doe
If, on palpating, no embryos are found to be present, the doe has
failed to conceive. If she is in proper physical condition, she may be
taken immediately to the buck's hutch for mating and then fed a ration
that is suitable in quantity and quality for a dry doe until a later test
demonstrates that she has conceived. In the ease of a doe of a medium-
4 LEAFLET 2 45, UNITED STATES DEPARTMENT OF AGRICULTURE
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4 —
7 8
FIGURE 3. — Horns of the uteri from three does showing uterine and embryonic
development of 10-, 14-, and 21-day pregnancies respectively.
weight breed, palpating 14 to 16 days after mating will save 6 to 8
pounds of feed that would otherwise have been consumed if she had
been allowed to go the full gestation period of 31 to 32 days before
rebreeding. The doe that is pregnant can be placed immediately on
a ration that is best suited for properly conditioning pregnant does.
It would be a good practice for the inexperienced person to palpate
again a week later the does that have been diagnosed as nonpregnant.
If a mistake has been made at the first handling the doe may then be
given the nest box at the proper time if she is due to kindle.
In palpating the doe at as early as the 7th to 8th days following
mating, one must make sure that he is not confusing pellet -shaped fecal
material in the large intestine with the small embryos in the horns of
the uterus. Confusion can be avoided by remembering that the horns
of the uterus lie at the bottom of the abdominal cavity while the large
intestine is at the top.
As the breeder becomes proficient in palpating and becomes ac-
quainted with the anatomy of the abdominal cavity, lie will also acquire
the ability to identify retained fetuses, abscesses or cysts on the gener-
ative or intestinal tract, inflamed or congested horns of the uterus, and
impaction of the cecum. Being able to diagnose these cases in this
manner will make it possible for the breeder to cull and dispose of the
does that will not breed, thereby saving feed and labor, and in infectious
cases remove individuals that may spread diseases in the herd.
Washington, D. C.
U. S. GOVERNMENT PR]
December 1946
1NG OFFICE: 1946
